Artificial white light is being adopted at a high rate. Such light sources can produce high quality light with a CRI (color rendering index) beyond 90 with very high efficiencies. However, one of the problems of such light sources as compared with sun light is the absence of certain parts of the spectrum which have specific benefits to humans beyond providing visible light. For example, UV light (albeit at very low intensities) is very important for production of vitamin D (or for skin tanning, insect attraction, skin treatment, etc.). For this purpose, it is possible to introduce a UV LEDs in combination with white LEDs.
US2014160728 discloses a light emitting device which comprises: a plurality of light emitting devices including a blue light emitting device emitting blue light and a UV light emitting device emitting ultraviolet light; and a wavelength conversion part arranged in the path of the light emitted from the plurality of light emitting devices, and provided with fluorescent substances to convert the wavelengths of the light emitted from the plurality of light emitting devices, wherein a fluorescent substance excited by and mixed with the blue light to obtain white light is arranged on a first area corresponding to the blue light emitting device, and at least a blue fluorescent substance is arranged on a second area corresponding to the UV light emitting device.
However, UV point light sources are very harmful to the skin and if a person touches or come close to it for too long it can lead to different problems. Also it is uncomfortable to look into light source with a high glare.